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Full text of "The Morphology And Evolution Of The Apes And Man"

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THE NEEVOUS  SYSTEM                  315
cut off Man  suffers  from  vertigo,  particularly in the dark, or when he closes his eyes.
In the Chimpanzee the eyebrows are poorly developed, for they are merely represented by a few short hairs-The eyelids have well-marked meibomian follicles, which, however, may be concealed by pigmented conjunctiva. The lacus lachrymalis is wide, but has no caruncle; and the plica semilunaris is well marked. The lower lachrymal papilla is larger than the upper one. The lachrymal gland is small, flat and divided into two parts. And the lachrymal sac and ducts are much as in Man. The orbital fat is in good amount.
The globe of the eye is similar to that in Man, and the ophthalmoscopic appearances are similar also (93).
The ocular muscles in the Chimpanzee arise as in Man, and they are innervated in the same way. The four musculi recti are inserted as in Man, but their relations to the structures in the orbits differ somewhat from those in him. The levator palpebrae superioris has no attachment to the skin, but is fixed to the superior tarsal cartilage and conjunctiva. The superior oblique muscle is more spread out after it passes through the trochlea than in Man. But the inferior oblique, which is inserted into the back of the eyeball, has a narrower insertion than in him. In the Orang, according to Ottley (272), the inferior oblique muscle is inserted farther forwards on the globe.
The External Ear.—During the process of evolutioji structures become increasingly complex and specialized,